Patent GB-894435-A (GB)
Title: Herbicidal compositions
IPC: C07C65/05
Filed: 1959-08-04
Abstract: 2-methoxy-3,5-dichlorobenzoic acid is prepared by treating salicylic acid with gaseous chlorine in acetic acid solution at a temperature below 35 DEG C., dissolving the resulting 3,5-dichlorosalicyclic acid in aqueous sodium hydroxide and refluxing with dimethyl sulphate, adding further sodium hydroxide, refluxing and then acidifying the product. 2-methoxy-3.5-dibromobenzoic acid is prepared by treating the salicyclic acid with hydrogen bromide instead of chlorine in the above process.  a -chlorophenylacetic acid is prepared (a) by heating mandelic acid to 140 DEG C. with concentrated hydrochloric acid (b) by the action of potassium hydroxide on trichloromethylphenylcarbinol (c) by the chlorination of phenylacetic acid and (d) by the action of water on the acid chloride obtained from mandelic acid and phosphorus pentachloride. a -chlorophenylacetic acid is converted to a ,a -dichlorophenylacetic acid by treating the melted monochloro compound with gaseous chlorine, preferably under illumination from actinic light.  2,6-dimethoxy-3-chlorobenzoic acid is prepared by treating 2,6-dihydroxyacetophenone in aqueous sodium hydroxide with dimethyl sulphate made basic to give 2,6-dimethoxyacetophenone, which is then heated with sodium hypochlorite and acidified. 2-amino-3,5-dichlorobenzoic acid is prepared by treating 3,5-dichlorobenzoic with fuming nitric acid, the 2-nitro-3,5-dichlorobenzoic acid produced is dissolved in ammonium hydroxide, refluxed with aqueous ferrous sulphate and acidified. 2,6-dichloro-3-methoxybenzoic acid is obtained by treating 2,6-dichloro-3-hydroxy-benzaldehyde in aqueous sodium bicarbonate with dimethyl sulphate, the methyl ether produced is refluxed with aqueous potassium permangenate containing sodium bicarbonate, treated with sodium bisulphite and acidified. 2-chloro-5-methoxybenzoic acid is similarly prepared from 2-chloro-5-hydroxybenzaldehyde. 2-Methoxy-3,5-dinitrobenzoic acid is prepared by cooling 2-methoxybenzoic acid with concentrated sulphuric acid to 25 DEG C. and adding concentrated nitric acid. 2-methoxy-3-methyl-5-chlorobenzoic acid is prepared by treating 3-methyl-5-chlorosalicyclic acid in aqueous sodium hydroxide with dimethyl sulphate.  2-amino-3,5,6-trichlorobenzoic acid is prepared by treating 3,4,6-trichlorophthalimide with sodium hypochlorite or by oxidising 4,5,7-trichloroisatin with hydrogen peroxide in a basic medium.  The anhydride of 3-methoxy-2,6-dichlorobenzoic acid is prepared by dissolving the acid chloride of 3-methoxy-2,6-dichlorobenzoic acid in a mixture of pyridine and benzene and adding the free acid thereto, the acid chloride being prepared by the action of phosphorus trichloride on the free acid. The sodium salt of 2-methoxy-3,5-dichlorobenzoic acid is prepared by treating the free acid with sodium hydroxide in methanol solution and the butyl ester of the free acid is obtained by refluxing the free acid with butyl alcohol in benzene in the presence of p-toluenesulphonic acid.  The diethanolamine salt of 2,6-dimethoxy-3-chlorobenzoic acid is obtained by treating the free acid in dry ether with diethanolamine and the N,N-diethylamide of the free acid is prepared by treating the acid chloride of 2,6-dimethoxy-3-chlorobenzoic acid with diethylamine in benzene solution.  The amide of 3-methoxy-2,6-dichlorobenzoic acid is obtained by treating the acid chloride of the free acid with dry ammonia gas in benzene solution.  The anhydrides, salts, esters and amides of the other chlorinated benzioc acids and phenyl acetic acids specified may be similarly prepared.ALSO:A herbicidal composition comprises a solid carrier or a surface-active agent or a solid or liquid carrier and a surface-active agent and one of the following compounds as active ingredient: 2 - methoxy - 3,5 - dichlorobenzoic acid, 2 - methoxy - 3,5 - dibromobenzoic acid, alpha - chlorophenylacetic acid, alpha-alpha-dichloro-phenylacetic acid, 2-amino-3,5-dichlorobenzoic acid, 2,6 - dimethoxy - 3 - chlorobenzoic acid, 2 - methoxy - 3,5 - dinitrobenzoic acid, 3 - methoxy - 2,6 - dichlorobenzoic acid, 2 - chloro - 5 - methoxybenzoic acid, 2 - methoxy - 3 - methyl - 5-chlorobenzoic acid and 2 - amino - 3,5,6, - trichlorobenzoic acid.  The compound may be in the form of the free acid, the acid anhydride, a salt, an amide or an ester.  The amide may be a substituted amide, e.g. the N-methyl, N-butyl, N-decyl, N,N-diethyl amide or an anilide and the N-alkyl group preferably contains 1 to 10 carbon atoms.  The composition may be formulated as a dust containing 5 to 25% of the active ingredient in the form of its alkali metal or ammonium salt using talcs or clays as carriers, or as a spray in an organic solvent, e.g. Xylene, kerosene, methylated naphthalenes or methanol containing a surface-active agent as an ester or as an amine salt in aqueous solution containing a surface-active agent, e.g. the diethylamine, triethylamine, diethanolamine, triethanolamine, isopropylamine and morpholine salts. The active ingredients may also be emulsified or suspended in water. If desired, pesticides, stabilizers, activators, synergists, spreaders and adhesives may be added to the composition.